I use 500 hp EM decks regularly for certain oracle predictions, since the payoff is higher that way. (probably not as time efficient, but I like big numbers
) When the arena first came out, I used it and made a lot of score even though it didn't win a lot of games. I think other decks are probably better against the arena, especially if your goal is special spins; if you just want score, it's alright, but even there, there's probably better ones.
I don't have a lot of stats for 500hp EM against oracle predictions, but against Jezebel I'm 3-0 and against Octane I'm 3-1. (started keeping track fairly recently) I'd expect those two to be almost sure things with 500hp EM, at least using the builds I have, which in both their cases use reflective shield. A few other FGs could probably be beaten if you used a rainbow 500hp EM for eternity; the two above were earth/light duos. Against Decay and Neptune, for example, a 500hp EM deck earth/light duo without eternity lost to deckout, paradoxically because they are the two worst FG decks :p Their hands clog up with stuff like flooding or siphon life or whatever and they stop double-drawing.
